Why Does Sand Stick to Everything?

Good luck getting that out of your car.
Good luck getting that out of your car. / YinYang/E+ via Getty Images

Relaxing at the beach feels good in the moment, but then come the consequences. Sand in your shoes. Sand stuck to your clothes, hands, and hair. Sand in your car. In your living room. In your bed. In your coffin at your funeral there will be sand. Its ability to adhere itself to everything and turn your life into a gritty endurance test is amazing. So why does it stick everywhere?

Actually, it doesn’t. Not without help, anyway. Sand is made up of decomposed quartz along with calcite, feldspar, gypsum, basalt, and even bits of shells. This concoction by itself isn’t sticky. It’s when sand gets wet that the problem begins.

According to Popular Science, sand is hydrophilic, meaning that it attracts water. Beaches, of course, tend to have moisture. So do humans, who sweat under the hot sun. The moment sand comes in contact with something wet—your feet, a towel, the ocean—it retains moisture, creating a sticky glob that wants to become a permanent fixture in your life.

Sunscreen can also help sand latch onto your skin. Then, when it dries later, it tends to fall off in your car or house. It can also get stuck in crevices, the tiny folds on your body (fingers, armpits, toes) that act as depositories for the grains.

You can minimize how much sand you take back with you by using mesh bags that can easily be shaken out. Some people even use talc to prevent sand from sticking to their bodies in the first place. If all else fails, making use of a beach shower works.

If a little water is bad, why is more water good? Water likes to stick to rock surfaces, creating a kind of liquid bridge. But too much water breaks the bridge, allowing the sand to move freely again.

Wet sand actually promotes a larger hazard. Though it seems structurally sound when damp, it will begin to move again when it’s dry. That’s good for cleaning, but bad if you or your child has dug a hole in the beach. Wet sand that looks safe will collapse, which can be dangerous and even deadly for someone who gets trapped in the hole. (The same holds true for young birds, who may have trouble navigating out of a trench left behind by beachgoers.)

If sand has all these properties, why does it seem like professional volleyball players stay sand-free? It turns out that the official rules of the competitive game call for sand “sifted to an acceptable size” that’s less likely to retain water.

Wet sand can range from mildly annoying to potentially lethal. Please enjoy sand responsibly.

[h/t Popular Science]

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